Calculate gravel volume
Enter the dimensions of the stone-filled zone, not automatically the full excavation depth. If soil or top cover sits above the stone, leave that cover out of the stone depth.
What this calculator actually measures
The starting volume is simple rectangular geometry: length × stone-zone width × stone-zone depth. Wrivel then subtracts the geometric volume occupied by a round pipe running the full entered length. That leaves an estimated aggregate volume before the optional ordering allowance.
This is a material-volume estimate, not a French-drain design. It does not decide trench depth, pipe diameter, aggregate gradation, geotextile details, hydraulic capacity, outlet elevation or whether the system should be installed.
Why stone depth is not always excavation depth
A trench can contain soil cover, surface material, pipe, bedding and aggregate in different proportions. If the upper portion will be backfilled with soil rather than aggregate, entering the full excavation depth will overstate gravel quantity. Measure the part you actually intend to fill with stone.
Example: 50 ft × 18 in × 24 in
A 50-foot stone zone that is 18 inches wide and 24 inches deep has a gross rectangular volume of 150 cubic feet, or about 5.56 cubic yards, before pipe displacement. A 4-inch pipe removes only a small part of that geometric volume. The ordering allowance then applies to the net stone volume—not to the pipe.
Why Wrivel does not convert this directly to tons
Aggregate weight depends on stone type, grading, moisture, voids and the supplier's bulk-density basis. Two suppliers can quote the same nominal stone differently. Use the calculated cubic yards or cubic metres when asking the local supplier what weight or delivered quantity corresponds to that material.
Do not confuse gravel volume with water-storage volume
The aggregate itself occupies most of the trench. Only the void space between particles can hold water. If you are estimating temporary storage rather than material quantity, use the dry-well storage screen, where the void fraction is explicit.
Before ordering material
- Route length is measured along the real path, including bends.
- Stone-zone width and depth reflect the actual section, not a generic online detail.
- Pipe outside diameter matches the selected product.
- Outlet, elevations and utilities are checked before excavation.
- Supplier confirms how its aggregate is sold: volume, weight or both.
- A contingency percentage is chosen intentionally rather than hidden in the result.